Troubleshooting · 8 min read · 2026-07-09
EcoFlow DELTA 2 Solar Capped at 8A: XT60i Middle Pin Fix
The EcoFlow DELTA 2’s solar input port accepts up to 500W at 11–60V — one of the widest input windows in its class. But there is a hidden constraint: the port uses an XT60i connector, an EcoFlow-modified version of the standard XT60 with a signal pin in the centre. That middle pin is what tells the DELTA 2 whether it is receiving solar input or car (DC) input. Without it, the unit defaults to car mode, caps at 8A, and your 300W panel delivers at most 160W into the battery.
A thread on the DIY Solar Power Forum documented this precisely: “The extra middle pin on the XT60i plug is what tells the Delta 2 if your input is car or solar. You need a cable with the middle pin grounded to the negative, for the d2 to switch to solar input and remove the 8A/24V limits.” (DIY Solar Power Forum) The owner had connected third-party panels through a standard MC4-to-XT60 cable and was seeing input numbers far below what the panel should deliver. The panel was working. The MPPT was working. The cable was the problem. This guide explains exactly how the XT60i signal works, how to identify whether your cable has the correct wiring, and how to confirm solar mode is active.
How the DELTA 2 decides between car and solar mode
The DELTA 2 has two distinct DC input modes with different operating envelopes. Car mode is designed for 12V vehicle sockets and accepts 12–30V at up to 8A — appropriate for a car’s 12V DC auxiliary output. Solar mode is designed for panel arrays and accepts 11–60V at up to 13A for up to 500W — a much wider window that can handle most single and multi-panel configurations. The unit uses the XT60i connector’s middle signal pin to determine which mode to apply. When the middle pin is grounded to the negative conductor inside the cable, the DELTA 2 reads a closed signal circuit and activates solar mode. When the middle pin is absent or floating (not connected), the signal circuit is open, and the unit defaults to car mode.
This design lets EcoFlow use a single physical port for both car and solar input without requiring the user to change any setting. Plug in an EcoFlow solar cable or extension cable with the middle pin correctly wired, and the DELTA 2 automatically enters solar mode. Plug in a car-to-XT60 cable or a standard MC4-to-XT60 adapter that lacks the middle pin, and the unit stays in car mode. The problem arises because most generic MC4-to-XT60 adapter cables are not built to EcoFlow’s XT60i spec — they only wire the two main power conductors and leave the middle pin absent or unconnected.
Identifying the symptom: capped input with no error
The car-mode-vs-solar-mode mismatch is subtle enough that many owners miss it for months. The DELTA 2 does not display an error or warning when it is in car mode with a solar panel connected. The EcoFlow app simply shows the input watts that the 8A cap allows. If you have a 200W panel in full sun and see 120–160W of input, the math fits: at roughly 20V panel operating voltage, 8A × 20V = 160W. It looks plausible. You might assume the panel is simply not performing at its nameplate rating and not investigate further.
The tell-tale sign of car mode is that the input never scales above what 8A at your panel’s operating voltage permits — regardless of how much sun you have, how direct the angle, or how high-wattage the panel is. A 400W panel in perfect sun delivering 30V × 8A = 240W is capped. A 200W panel at 18V × 8A = 144W is capped. The watts increase proportionally with the panel’s operating voltage, but the 8A limit means you never approach what the panel is actually capable of. If you suspect this, check the input in the EcoFlow app and compare it against your panel’s rated Vmp (operating voltage) multiplied by 8A. If the numbers match closely, you are in car mode.
Confirming the cable: what to look for
Pull the XT60 plug out of the DELTA 2’s solar port and look at the plug face — the side with the metal contacts. A standard XT60 plug has two large rectangular blades, one marked positive (+) and one marked negative (−). An XT60i plug compatible with the DELTA 2’s solar mode has an additional small round pin in the centre, positioned between the two main blades. This is the signal pin. On a correctly wired cable, this centre pin connects to the negative wire inside the cable jacket — it is physically connected to the negative conductor so that when the plug seats into the DELTA 2’s socket, the signal circuit is closed and the unit detects solar mode.
If your cable’s XT60 plug has only the two main blades and no centre pin, it is not an XT60i and will not signal solar mode. If you can see a centre pin but are unsure whether it is connected internally, a multimeter confirms it: set the meter to continuity mode, touch one probe to the centre pin and the other to the negative conductor on the MC4 end of the cable. A beep or a near-zero resistance reading confirms the connection. No continuity means the centre pin is not wired to the negative and the cable will not enable solar mode.
The fix: which cables to use
The most reliable fix is to use an EcoFlow-branded cable, which is guaranteed to have the correct XT60i wiring. EcoFlow sells 2-metre and 5-metre solar extension cables with the XT60i connector on one end and XT60 or MC4 on the other. These cables are designed specifically for EcoFlow units and the middle pin is correctly wired from the factory. EcoFlow also sells MC4-to-XT60i adapter cables for connecting standard MC4-equipped panels.
If you prefer third-party options, search for cables explicitly described as “EcoFlow XT60i solar cable” or “MC4 to XT60i with signal pin.” A listing that does not mention XT60i or the three-pin connection is almost certainly a standard MC4-to-XT60 cable that will leave you in car mode. The price difference is small — a proper XT60i cable typically costs $10–20 — and the performance difference is substantial: on a 400W panel under full sun, the difference between car mode (8A cap) and solar mode (13A) is approximately 100–160W of additional input.
Verifying solar mode is active after switching cables
After installing a correctly wired XT60i cable, confirming solar mode takes about 30 seconds in the EcoFlow app. Set the panel in full sun, connect it via the new cable, and open the app. Navigate to your DELTA 2’s device view and look at the input reading. In solar mode with a 200W panel in direct summer sun, you should see somewhere between 140W and 190W of real input — significantly higher than the 8A-capped reading from before. If the input is still similar to what you saw with the old cable, check that the plug is fully seated in the solar port (it should click into place without wobble) and that the new cable’s centre pin is making contact.
One common mistake after switching cables is not fully inserting the XT60i plug. The centre pin sits slightly proud of the two main blades and requires full insertion to make contact with the corresponding socket in the DELTA 2. A half-seated plug will connect the power blades but miss the signal pin — the unit will accept power but remain in car mode. Push the plug in firmly until it seats fully; there should be no forward-backward play in the connector when it is correctly inserted. After that, solar mode is automatic and persistent across power cycles — you do not need to reconfigure anything in the app each time you connect. For a complete reference on maximising solar input from your DELTA 2, see our DELTA 2 solar panel wiring guide.
FAQ
Why is my DELTA 2 solar input limited to 8A even though I have a large panel?
The DELTA 2 uses the middle pin on its XT60i solar input connector to detect whether the connected cable is solar or car (DC) input. When a third-party MC4-to-XT60 adapter cable lacks the middle pin or leaves it ungrounded, the DELTA 2 defaults to car input mode, which caps input at 8A and applies a lower voltage range appropriate for 12V car sockets. The fix is to use a cable with the middle pin correctly grounded to the negative conductor, which signals solar mode and unlocks the full 500W ceiling.
What is the XT60i connector and how is it different from a standard XT60?
The XT60i is EcoFlow's modified version of the standard XT60 connector. It adds a third small signal pin in the centre of the connector housing. This signal pin carries no power; it is a detection signal that tells the DELTA 2 what type of input is connected. In solar mode (middle pin grounded to negative), the DELTA 2 accepts 11-60V Voc and up to 13A for up to 500W total. Without the middle pin grounded, the DELTA 2 treats the input as a car DC port and applies the car input constraints: 12-30V range and 8A maximum.
How do I check if my cable has the XT60i middle pin correctly wired?
Look at the XT60 end of your MC4-to-XT60 cable. The XT60i socket on the DELTA 2 has three contact points: two large power blades (positive and negative) and a smaller pin in the centre. A correctly wired solar cable should have a corresponding pin in the XT60 plug that contacts this centre position and connects it to the negative conductor inside the cable. If your cable's XT60 plug only has the two main blades and no centre pin, it will not signal solar mode. Use a genuine EcoFlow solar extension cable or an MC4-to-XT60 cable marketed specifically for EcoFlow solar input.
Will using a standard XT60 cable damage the DELTA 2?
No — using a cable without the middle pin grounded does not damage the unit. The DELTA 2 simply applies its car-mode input limits as a safe default. Your panels will charge the unit, just at a reduced rate determined by the 8A cap. A 300W panel producing 15A at 20V will deliver only 160W (8A × 20V) instead of 300W. The unit is protecting itself from non-signalled high-current input, not experiencing a fault. Switch to a correctly wired XT60i cable and the full charging speed returns immediately.
Where can I get a correct XT60i solar cable for the DELTA 2?
EcoFlow sells official solar extension cables (2m and 5m lengths) that include the correct XT60i plug with the middle pin wired. These are available from EcoFlow's website and authorised dealers. If you prefer a third-party option, search specifically for 'EcoFlow DELTA 2 MC4 to XT60i solar cable' — the listing should explicitly mention XT60i or the three-pin connection. A standard MC4-to-XT60 cable from a generic electronics supplier will not have the middle pin and will not trigger solar mode.